The present invention relates to a new and improved construction of a yarn rupture-suction installation, more conventionally termed broken end-collecting installation for the drafting systems or drafting arrangements of spinning machines, there being provided a respective suction head for each drafting system which is connected with an air pressure sink and having a substantially slot-shaped opening associated with the feed or delivery roller of the related drafting system. The invention further concerns a novel method of operating such installation to prevent clogging of the suction head.
In spinning machines it is already known for quite some time to equip the drafting systems or drafting gears with suction devices for ruptured yarn or the like, as such for instance has been disclosed in British Patent No. 951,209. The suction devices possess suction tubes or pipes which are connected at one end thereof with a suction channel which extends in the lengthwise direction of the machine below for instance the creel, whereas the other end of each such suction tube forms a suction opening. According to certain types of constructions of such equipment, a suction tube is provided for each drafting system, the suction opening of which, as a general rule, is disposed below the lower feed or delivery roller at the neighborhood of the yarn or thread path of travel extending to the spindle.
Apart from the foregoing, there is also already known to the art a device arranged at a ring spinning machine, wherein there is provided, apart from a suction opening associated with the lower feed roller of each drafting system, also a suction opening associated with the upper feed or delivery roller. Due to this arrangement it is intended that one end of the ruptured yarn or thread, which is not engaged by the suction opening of the lower feed roller, will be seized by the suction opening of the upper feed roller during ascent towards such upper feed roller.
The state-of-the-art yarn rupture-suction installations or broken end-collecting installations are not capable of satisfying the present-day requirements for a different reason. Upon occurrence of yarn or thread rupture, the thread or the like is usually engaged with adequate reliability. But, on the other hand, oftentimes there occurs shortly after engagement or seizing of the thread clogging of the suction tube at the neighborhood of the suction opening, producing the well-known undesirable consequences.
Examination of the cause of such clogging has shown that yarn or thread rupture at flyer-spinning machines occurs with relatively increasing frequency at the press or contact finger and yarn rupture at ring spinning machines often occurs directly at the travellers. Consequently, upon occurrence of yarn rupture there is engaged by the suction opening, not only fiber material which is delivered by the drafting system, but also such roving or yarn whose free end is retained at the flyer or in the case of a ring spinning machine, at the thread or yarn guide. The outflow of the further delivered fiber material through the suction opening therefore can be hindered by such yarn at the region of the suction opening. A further difficulty which is additionally present is that the twist present at such section of fiber material or formed by the operation of the specific machine, causes a curling of the yarn in the suction tube and a braiding of the fiber material which is further delivered by the drafting system.